Ofcom has warned that Ofcom's plan to replace copper-based broadband lines with a full-fibre alternative could push up bills for consumers.
The infrastructure body has recently consulted with communications providers to identify the level of demand for a major full-fibre deployment, with a view to supplying fibre to ten million premises by 2025.
However, Ofcom is concerned because Openreach has told major broadband providers that it would have to raise wholesale broadband costs in order to pay for new upgrades.
Indeed, the infrastructure body wants to add £7 per month to the wholesale cost of broadband in order to get a return on investment.
As a result, the likes of Sky and TakTalk could be forced to pass these costs onto consumers.
Sharon White, Ofcom's Chief Executive, commented: "We welcome Openreach’s commitment to reach two million homes with full-fibre by 2020.
"The company has also outlined plans to reach ten million by the mid-2020s, but dependent on up to £7 a month being added to broadband bills."
Ms White acknowledged that major operators must juggle competing priorities, such as investing in broadband infrastructure and paying for sports or other content rights.
However, she said "the national priority is clear", as competition and consumer demand for fibre are growing.
"As the owner of Openreach - the national telecoms network which is becoming more independent from BT - it should act in the interest of all of its customers who rely on it, as well as its shareholders," Ms White stated.
She added that if all the major broadband providers "come good on their public commitments", full-fibre broadband will reach up to one-fifth of the country by 2020.
This, she said, would be a step forward from the current figure of three per cent, but still leave the UK "trailing" other countries.
"To catch up, we need still bolder commitments," Ms White insisted.
Responding to the comments, an Openreach spokesman said continuing to invest "remains a priority for us and we’re encouraged that our wholesale customers support our ambition".
However, he told the Telegraph that investing in a major Fibre-to-the-Premises network needs "commitment from the whole industry".
"We’re engaging with Ofcom and government to build an environment that encourages and facilitates investment," the spokesperson said.